These coins can never be worth less than their weight in gold. To find the base value (BV) multiply the gold content by the current price of gold. Look it up, as it changes every day. At this writing, gold is trading at $1330 US dollars per troy ounce, so BV for a 10 pesos is 0.1766 x 1330 = $235.

To find approximate values, add a collector premium for coins in good condition: